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(11) | EP 0 313 369 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A polishing machine for polishing a gemstone |
| (57) A polishing machine (70) for polishing a gemstone (32) includes a support arrangement
(76) movably mountable relative to a polishing means (14). A holding means (102) for
holding the gemstone to be polished is rotatably mounted on the support arrangement
(76) and is movable together with the support arrangement (76) to move the gemstone
into and out of contact with the polishing means. A drive means (112) is provided
for rotatably driving the holding means relative to the support arrangement. The machine
(70) includes a control means (130) for controlling operation of the said drive means
(112) and thus the rotation of the holding means (102) relative to the support arrangement
(76). A monitoring means (126) monitors a polishing rate of the gemstone at each of
a plurality of predetermined positions of a revolution of the holding means (102)
about the support arrangement (76) and sends data representative of the polishing
rate at the said positions of the holding means (102) to the control means, the control
means (130) controlling the drive means (112) to position the holding means (102)
at that position at which the said optimum polishing rate is achieved. |